19-5797; Rev 2; 12/11 DS3920 Fast Current Mirror General Description The DS3920 precision current mirror is designed for avalanche photodiode (APD) and PIN photodiode biasing and monitoring applications. The device offers a current clamp to limit current through the APD and a current mirror output that produces a signal proportional (5:1) to the APD current. A diode is also provided to limit the voltage at the current mirror output. Features SWide Voltage Input Range: 2.97V to 76V SCurrent Monitor Wide 250nA to 2mA Range 5:1 Mirror Ratio Fast 50ns Time Constant SCurrent Clamp (4.4mA or 20mA, typ) The device accepts a +2.97V to +76V current mirror supply voltage. Internal current limiting (4.4mA or 20mA, typ) protects the monitored device from a short circuit to ground. The provided internal clamp diode protects the current mirror output from overvoltage. Additionally, the device features thermal shutdown if the die temperature reaches +150NC. SVoltage Clamp Protects Subsequent Output Circuitry The device is available in a 6-pin SOT23 package, and operates over the -40NC to +85NC extended temperature range. GEPON, GPON, 10GEPON, XGPON: ONU and OLT S6-Pin SOT23 (MAX4007 Compatible) Applications Avalanche Photodiode (APD) Biasing PIN Photodiode Monitoring Ordering Information appears at end of data sheet. Typical Application Circuit APD BIAS RFILTER 100Ω–1000Ω 3.3V MIRIN DIODE CFILTER 0.1μF CURRENT MONITOR IMIROUT GND IMIROUT/5 THERMAL SHUTDOWN MIR CURRENT LIMIT DS3920 MIROUT IMIROUT/5 VOUT ROUT 1kΩ–5kΩ RAGC 499Ω ROSA APD TIA For related parts and recommended products to use with this part, refer to: www.maxim-ic.com/DS3920.related ����������������������������������������������������������������� Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. DS3920 Fast Current Mirror ABSOLUTE MAXIMUM RATINGS Voltage Range on MIRIN, MIROUT, and DIODE Relative to GND .............................-0.3V to +80V Voltage Range on MIR Relative to GND .............................. -0.3V to (VDIODE + 0.6V) Continuous Power Dissipation (TA = +70NC) SOT23 (derate 13.4mW/NC above +70NC)..............1072.4mW Operating Junction Temperature Range.......... -40NC to +150NC Storage Temperature Range............................. -55NC to +135NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VMIRIN = 2.97V to 76V, TA = -40NC to +85NC, unless otherwise noted.) PARAMETER SYMBOL MIRIN Voltage VMIRIN MIRIN Current IMIRIN Diode Forward Current MIN TYP 2.97 IMIROUT = 2.5mA IDF Diode Forward Voltage VDF MIROUT Current Limit IMIROUT MIROUT Series Resistance CONDITIONS RAGC MAX UNITS 76 V 4.4 mA 5 mA 0.6 IDF = 100FA, TA = +25NC IDF = 5mA, TA = +25NC 1.25 DS3920T-001 version, TA = +25NC 10 20 40 DS3920T-002 version, TA = +25NC (Note 1) 2.8 4.4 8 100 V mA W 1FA to 2.5mA 0.190 0.200 0.210 IMIROUT > 2.5mA 0.180 0.200 0.220 VMIRIN = 3V (Note 2) 4800 15,000 VMIRIN = 30V or 60V (Notes 2, 3) 100 500 tRC (Note 4) 30 ns Thermal Shutdown Temperature TSHDN (Note 3) +150 NC Thermal Shutdown Hysteresis THYST (Note 3) 20 NC MIR to MIROUT Ratio Power-Supply Rejection Ratio MIR Current Rise Time (20%/80%) Note Note Note Note 1: 2: 3: 4: KMIR (DIMIR/IMIR) /DVMIRIN A/A ppm/V See the Typical Application Circuit. 1V DC change applied to MIRIN; 100FA at MIROUT; 4.99kI load to ground on MIR. Guaranteed by design; not production tested. Rising MIROUT transition from 10FA to 1mA; 15V < VOUT < 76V. ����������������������������������������������������������������� Maxim Integrated Products 2 DS3920 Fast Current Mirror Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) MIRIN CURRENT vs. MIRIN VOLTAGE IMIROUT = 2.5mA DS3920 toc02 MIRIN CURRENT vs. MIROUT CURRENT 100 DS3920 toc01 10 VMIRIN = 40V 10 IMIRIN (mA) IMIRIN (mA) 1 0.1 1 IMIROUT = 1µA 0.1 0.01 0.001 0.01 20 40 60 80 0.01 VMIRIN (V) MIRIN CURRENT vs. TEMPERATURE 1 10 GAIN ERROR vs. MIROUT CURRENT 5 DS3920 toc03 10 IMIROUT = 2.5mA IMIRIN (mA) IMIROUT = 1µA VMIRIN = 40V 4 3 GAIN ERROR (%) 1 0.1 0.1 IMIROUT (mA) DS3920 toc04 0 2 1 0 -1 -2 -3 -4 VMIRIN = 40V 0.01 -40 -15 10 35 60 -5 0.001 85 0.01 TEMPERATURE (°C) DS3920 toc06 1.5 GAIN ERROR (%) GAIN ERROR (%) 1 0 IMIROUT = 250µA IMIROUT = 10mA -2 0.5 IMIROUT = 1µA IMIROUT = 2.5mA 0 IMIROUT = 5mA -0.5 -1.0 -3 IMIROUT = 10mA -1.5 -4 VMIRIN = 40V -5 -40 -15 10 10 1.0 2 -1 2.0 DS3920 toc05 IMIROUT = 1µA IMIROUT = 2.5mA 3 1 GAIN ERROR vs. MIRIN VOLTAGE GAIN ERROR vs. TEMPERATURE 5 4 0.1 IMIROUT (mA) 35 TEMPERATURE (°C) 60 -2.0 85 0 20 40 60 80 VMIRIN (V) ����������������������������������������������������������������� Maxim Integrated Products 3 DS3920 Fast Current Mirror Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) TRANSIENT RESPONSE (VMIRIN = 40V) STARTUP DELAY (VBIAS = 40V, IMIROUT = 1µA) DS3920 toc07 STARTUP DELAY (VMIRIN = 40V, IMIROUT = 2.5mA) DS3920 toc08 40V CH1 A MIR 0V R2 5kΩ 40V CH1 CH1 MIRIN D.U.T DS3920 toc09 MIROUT CH2 R1 38MΩ CH1 MIR 0V R2 5kΩ MIRIN D.U.T MIROUT CH2 R1 15.6kΩ 40V MIR CH2 B MIRIN D.U.T MIROUT CH1 CH2 CH2 0V 0V 5kΩ 100kΩ 5kΩ 500ns/div 200µs/div A: CH1, 1V/div, IMIROUT = 375µA TO 7.5mA A: CH2; 5V/div, IMIR = 75µA TO 1.5mA 200µs/div CH1: 20V/div CH2: 20V/div CH1: 20V/div CH2: 20V/div STARTUP DELAY (VMIRIN = 5V, IMIROUT = 1µA) STARTUP DELAY (VMIRIN = 5V, IMIROUT = 2.5mA) DS3920 toc10 DS3920 toc11 5V 5V CH1 CH1 MIR R2 5kΩ 0V CH2 MIRIN D.U.T CH1 CH1 MIROUT CH2 R1 4.6MΩ MIR R2 5kΩ 0V MIRIN D.U.T MIROUT CH2 R1 1.7kΩ CH2 0V 0V 200µs/div CH1: 2V/div CH2: 2V/div 200µs/div CH1: 2V/div CH2: 2V/div ����������������������������������������������������������������� Maxim Integrated Products 4 DS3920 Fast Current Mirror Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) SHORT-CIRCUIT RESPONSE (VMIRIN = 76V) DS3920 toc12 TA = +40°C A D E F C B B C D E F CH1 CH1 0A 0A 1.4 VMIRIN = 2.97V 1.2 VMIRIN - VMIROUT (V) A VOLTAGE DROP vs. MIROUT CURRENT DS3920 toc13 TA = +40°C 1.0 0.6 20ms/div CH1: IMIROUT, 5mA/div A: MIROUT SHORTS TO GND THROUGH 10Ω B: CURRENT LIMIT ACTIVE C: THERMAL SHUTDOWN D: POST COOL-DOWN REENTRY E: THERMAL SHUTDOWN F: POST COOL-DOWN REENTRY + DIODE 1 GND 2 MIR 3 DS3920 SOT23 TA = +100°C TA = +85°C 0.01 0.1 1 10 100 IMIROUT (mA) Pin Configuration TOP VIEW TA = +25°C 0.4 0 0.001 20ms/div TA = -40°C 0.8 0.2 CH1: IMIROUT, 5mA/div A: MIROUT SHORTS TO GND THROUGH 10Ω B: CURRENT LIMIT ACTIVE C: THERMAL SHUTDOWN D: POST COOL-DOWN REENTRY E: THERMAL SHUTDOWN F: POST COOL-DOWN REENTRY DS3920 toc14 SHORT-CIRCUIT RESPONSE (VMIRIN = 40V) Pin Description PIN NAME FUNCTION 1 DIODE Protection Diode. External potential used for voltage clamping of VMIR. If unused, this pin can be left unconnected. 6 MIRIN 2 GND Ground 5 N.C. 3 MIR Mirror Current Monitor Output, 5:1 Ratio 4 MIROUT 4 MIROUT Current Mirror Voltage Output. Connect to photodiode bias pin. Photodiode provides reference current for the mirror. 5 N.C. 6 MIRIN No Connection. Not internally connected. Current Voltage Bias ����������������������������������������������������������������� Maxim Integrated Products 5 DS3920 Fast Current Mirror Detailed Description The DS3920 provides a fast, precision current mirror for photodiode-monitoring applications. The current mirror is accurate across a large dynamic range. The mirror response time is fast enough to comply with GPON Rx burst-mode monitoring requirements. The device has a built-in current limiting feature to protect photodiodes from large signal inputs, and an included thermal shutdown. A diode is provided to limit the voltage at the MIR output. Current Mirror The mirror output is typically connected to an analogto-digital converter (ADC) using a resistor to convert the mirrored current into a voltage. The resistor to ground should be selected so that the ADC’s full-scale voltage is reached when the maximum mirrored current is reached. For example, given that the maximum monitored current through the APD is 2mA, 1.25V ADC full scale, and a 5:1 mirror ratio, the correct resistor is approximately 3.2kI. Current Clamp The device features a current clamping circuit to protect the photodiode by limiting the amount of current from MIROUT to no more than IMIROUT. See the Ordering Information for available current clamp options. Diode Protection A diode is internally connected from the MIR to DIODE pins. This enables an external voltage applied to DIODE to limit the voltage on MIR. The voltage applied to DIODE should be equal to the desired VMIR limit minus the diode forward voltage drop, or VMIR - VDF. Thermal Shutdown As a safety feature, the device has a thermal shutdown circuit that turns off the MIROUT and MIR currents when the internal die temperature exceeds TSHDN. The thermal shutdown mechanism has a built-in hysteresis of THYST. Thus, the MIROUT and MIR currents resume once the device has cooled to TSHDN - THYST. The mirror response time is dominated by the amount of capacitance placed on the output. Ordering Information TEMP RANGE TYP CURRENT LIMIT (mA) DS3920T-001+ PART -40NC to +85NC 20 PIN-PACKAGE 6 SOT23 DS3920T-001+T -40NC to +85NC 20 6 SOT23 DS3920T-002+ -40NC to +85NC 4.4 6 SOT23 DS3920T-002+T -40NC to +85NC 4.4 6 SOT23 +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 6 SOT23 U6SN+1 21-0058 90-0175 ����������������������������������������������������������������� Maxim Integrated Products 6 DS3920 Fast Current Mirror Revision History REVISION NUMBER REVISION DATE 0 3/11 Initial release 1 8/11 Changed the MIROUT -002 version current limit value from 2.9mA (typ) to 4.4mA (typ); updated the Electrical Characteristics IMIROUT values for -002 version from 2mA (min), 2.9mA (typ), 4.4mA (max) to 2.8mA (min), 4.4mA (typ), 8mA (max) and added TA = +25°C test conditions 2 12/11 Added RFILTER and ROUT resistor values to the Typical Application Circuit DESCRIPTION PAGES CHANGED — 1, 2, 6 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2011 Maxim Integrated Products 7 Maxim is a registered trademark of Maxim Integrated Products, Inc.